<template>
    <div class="child">
      <h3>我是Child组件</h3>
      {{sum}}
    </div>
  </template>
  
  <script>
  import {ref} from 'vue'
  export default {
    name: "Child",
    async setup(){
      let sum = ref(0)
      let p = new Promise((resolve,reject)=>{
        setTimeout(()=>{
          resolve({sum})
        },3000)
      })
      return await p;
    }
  }
  </script>
  
  <style>
    .child{
      background-color: skyblue;
      padding: 10px;
    }
  </style>